Today, the Maryland, West Virginia, Pennsylvania and Delaware State Quarter Coins remember the placing of the western point of the Mason Dixon Line 249 years ago.
On the Mason & Dixon Line Preservation Partnership web site, an annotated version of their survey diary provides insights.
An excerpt from the background for the survey:
The technological problems were great and involved the application of much complex geodesy and astronomy, and the progress had been very slow.
The Proprietors had earlier become convinced that the local surveyors needed assistance and had petitioned the Astronomer Royal to recommend scientists of ability to execute the work.
Charles Mason and Jeremiah Dixon were the nominees. Their competence had been adequately established.
The former had a long record of distinguished service at the Royal Observatory, Greenwich, and the latter had established his reputation as an astronomer on eclipse and transit expeditions to determine the distance to the sun, i.e., solar parallax.
A contract was prepared which was signed by Mason and Dixon and the Proprietors on August 4, 1763.
They arrived in this country on the following November 15 and by highly scientific procedures over a period of fifty-eight months established the common boundaries of Pennsylvania, Delaware, Maryland, and Virginia.
The excellence of their work has been attested to in more recent times by checks by such a prestigious organization as the U.S. Coast and Geodetic Survey.
One cannot read the account of the controversy between the Penns and the Calverts without amazement that such a conflict of interest could arise and remain unresolved for eighty-two years.
Its causes were deep rooted. One basic reason, earlier mentioned, was the careless practice of English royalty of assigning territorial rights that previously had been granted to others.
The situation was complicated by the lack of good maps, but this could have been obviated by a little systematic cartographic work by the English government.
Kings lacked competence in scientific matters and in the writing of their colonial charters made impossible geometrical specifications.
As there were able scientists in England whose advice would have averted the resulting confusion, this defect in their official acts is difficult to excuse.
An example is the specification of a “right line” on an ellipsoid of revolution.
Adjudication was hampered by lack of rapid transportation.
Frequently there was a tendency to argue matters to which a definite physical answer was easily available, as was the case with the location of the fortieth parallel of north latitude along the Delaware River, which was easily determinable by a competent surveyor.
Again, there was the problem of impossible specifications, an example being the failure of a circle of twelve miles radius centered in the belfry of New Castle courthouse to reach the fortieth parallel of north latitude.
There were also the untenable positions assumed by the respective disputants, examples being the arguments regarding the radius of the “circle at twelve miles distance” and also the disagreement over the distance from the Atlantic to the Chesapeake.
Perhaps the most untenable of all these positions was the proposal by commissioners that linear distances be measured up hills and down valleys, which would have precluded any type of mathematical check on the work.
A further source of trouble was that English courts did not appear consistent in their decisions and were given to political bias.
For example, the cryptic Latin phrase “hactenus inculta” was interpreted as favoring Maryland in the matter of Virginia settlements but decided against Maryland in the matter of the Dutch and Swedes, who actually were not in that area at the date of the granting of its charter.
To argue that King Charles I introduced this Latin phrase for the protection of the Dutch and Swedes requires the greatest elasticity of the imagination.
The fact is that the English had been continually concerned lest their middle Atlantic seaboard would be permanently severed by these settlements.
Then there seems to have been nothing final about the decrees of the English courts.
At one time procrastination was plainly a cause of the third Lord Baltimore’s difficulty, as he had his full forty degrees within his grasp but he failed to have a survey conducted.
The land areas lost by Maryland and Virginia (now West Virginia) to Pennsylvania were about 4,300 square miles and 1,100 square miles respectively.
The southern boundary of Pennsylvania was actually placed 19.27 statute miles below the fortieth parallel of north latitude.
As Delaware later became an autonomous jurisdiction, it is not here considered.
It is difficult to contravene the position of Maryland as having the earlier grant, but the position of the Penns seems to have been stronger in circles of English diplomacy.
The annotated manuscript summarized the survey party’s October 1767 activities:
October, I767. The work proceeded in continuing the boundary survey westward.
A messenger was dispatched to Fort Cumberland to obtain additional helpers for the survey party and on the seventh the party was again fully staffed.
The extension of the line continued and crossed an Indian war path at 231 miles 20 chains.
This was near a town which had been burned and most of the inhabitants killed in an Indian massacre in 1755.
On the ninth the chief of the Indians who were acting as deputies declared that the war path just reached “was the extent of his commission from the Chiefs of the Six Nations” and that he would proceed no farther.
All the Indian deputies now began to protest against any additional extension of the line, but nevertheless, Mason and Dixon continued for nearly 2 more miles and concluded the boundary demarcation at a distance of 233 miles 17 chains 48 links from the Post marked West.
The sector was set up at a distance of 233 miles 13 chains 68 links and latitude observations were taken from the eleventh to the eighteenth.
These showed that the sector was 2.23 seconds or 223 feet south of the parallel and this distance was measured off to the northward to reach the true boundary.
A table of offsets for the last 10-minute arc of great circle was now computed and the remainder of the month was spent in measuring such offsets from the arc of great circle actually run.
A note after their calculations in their diary for October 18, 1767 described the placement of the “W” post:
Note: The Sector stood on the top of a very lofty Ridge, but when the Offset was made of 3 Chains 38 Links it fell a little Eastward of the top of the Hills; we therefore extended the true Parallel 3 Chains 80 Links Westward which fell on the top of the said Ridge; there viz. at 233 Miles 17 Chains 48 Links from the Post marked West in Mr. Bryan’s Field, we set up a Post marked W on the West Side and heaped around it Earth and Stone three yards and a half diameter at the Bottom and five feet High. The figure nearly conical.
A chain is 66 feet long and contains 100 links.
Eighty chains equal a statute mile.
One link is 7.92 inches.
The Maryland, West Virginia, Pennsylvania and Delaware State Quarter Coins show with an image of a Mason Dixon marker, circa 1933.